A closer look at Arctic ozone loss and polar stratospheric clouds

Harris, Neil; Lehmann, Ralph; Rex, Markus; Gathen, Peter von der

doi:10.5194/acp-10-8499-2010

Cited by 53 publications

(73 citation statements)

References 46 publications

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“…Diagnostics using meteorological conditions to assess the potential for chemical processing, especially PSC formation and chlorine activation, are commonly used. Some of these diagnostics, such as the volume of air below PSC temperature thresholds (V PSC ), have been found to have strong links to total column ozone depletion (e.g., Rex et al, 2004;Tilmes et al, 2006;Harris et al, 2010). While some studies have linked changes in V PSC to an expectation of colder winters and greater ozone loss in the Arctic to global climate change (Rex et al, 2004, others do not support this conclusion (Hitchcock et al, 2009;Pommereau et al, 2013;Rieder and Polvani, 2013).…”

Section: Introductionmentioning

confidence: 75%

Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses

et al. 2015

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Abstract. We present a comprehensive comparison of polar processing diagnostics derived from the National Aeronautics and Space Administration (NASA) Modern Era Retrospective-analysis for Research and Applications (MERRA) and the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis (ERAInterim). We use diagnostics that focus on meteorological conditions related to stratospheric chemical ozone loss based on temperatures, polar vortex dynamics, and air parcel trajectories to evaluate the effects these reanalyses might have on polar processing studies. Our results show that the agreement between MERRA and ERA-Interim changes significantly over the 34 years from 1979 to 2013 in both hemispheres and in many cases improves. By comparing our diagnostics during five time periods when an increasing number of higher-quality observations were brought into these reanalyses, we show how changes in the data assimilation systems (DAS) of MERRA and ERA-Interim affected their meteorological data. Many of our stratospheric temperature diagnostics show a convergence toward significantly better agreement, in both hemispheres, after 2001 when Aqua and GOES (Geostationary Operational Environmental Satellite) radiances were introduced into the DAS. Other diagnostics, such as the winter mean volume of air with temperatures below polar stratospheric cloud formation thresholds (V PSC ) and some diagnostics of polar vortex size and strength, do not show improved agreement between the two reanalyses in recent years when data inputs into the DAS were more comprehensive. The polar processing diagnostics calculated from MERRA and ERA-Interim agree much better than those calculated from earlier reanalysis data sets. We still, however, see fairly large differences in many of the diagnostics in years prior to 2002, raising the possibility that the choice of one reanalysis over another could significantly influence the results of polar processing studies. After 2002, we see overall good agreement among the diagnostics, which demonstrates that the ERA-Interim and MERRA reanalyses are equally appropriate choices for polar processing studies of recent Arctic and Antarctic winters.

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Section: Introductionmentioning

confidence: 75%

Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses

et al. 2015

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“…The main processes leading to ozone reduction are the same over the two poles. Pronounced differences in stratospheric dynamics between the two hemispheres lead, however, to larger interannual variability in the stratospheric temperatures and in the vortex stability over the Arctic with respect to what occurs over the Antarctic (e.g., Harris et al, 2010). We lack a complete understanding of the mechanisms driving this variability and of potential effects that increasing greenhouse gases may have on these processes .…”

Section: Introductionmentioning

confidence: 99%

Ground-based stratospheric O<sub>3</sub> and HNO<sub>3</sub> measurements at Thule, Greenland: an intercomparison with Aura MLS observations

et al. 2013

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Abstract. In response to the need for improving our understanding of the evolution and the interannual variability of the winter Arctic stratosphere, in January 2009 a GroundBased Millimeter-wave Spectrometer (GBMS) was installed at the Network for the Detection of Atmospheric Composition Change (NDACC) site in Thule (76.5 • N, 68.8 • W), Greenland. In this work, stratospheric GBMS O 3 and HNO 3 vertical profiles obtained from Thule during the winters 2010 (HNO 3 only), 2011 and 2012 are characterized and intercompared with co-located measurements of the Aura Microwave Limb Sounder (MLS) experiment. Using a recently developed algorithm based on Optimal Estimation, we find that the GBMS O 3 retrievals show good sensitivity (> 80 %) to atmospheric variations between ∼ 17 and ∼ 50 km, where their 1σ uncertainty is estimated to be the larger of ∼ 11 % or 0.2 ppmv. Similarly, HNO 3 profiles can be considered for scientific use between ∼ 17 and ∼ 45 km altitude, with a 1σ uncertainty that amounts to the larger of 15 % or 0.2 ppbv. Comparisons with Aura MLS version 3.3 observations show that, on average, GBMS O 3 mixing ratios are biased negatively with respect to MLS throughout the stratosphere, with differences ranging between ∼ 0.3 ppmv (8 %) and 0.9 ppmv (18 %) in the 17-50 km vertical range. GBMS HNO 3 values display instead a positive bias with respect to MLS up to 26 km, reaching a maximum of ∼ 1 ppbv (10 %) near the mixing ratio profile peak. O 3 and HNO 3 values from the two datasets prove to be well correlated at all altitudes, although their correlations worsen at the lower end of the altitude ranges considered. Column contents of GBMS and MLS O 3 (from 20 km upwards) and HNO 3 (from 17 km upwards) correlate very well and indicate that GBMS measurements can provide valuable estimates of column interannual and seasonal variations for these compounds.

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“…Low TOC occurs mostly during the NAO positive phase, which leads to stationary planetary waves, stronger zonal winds, and therefore a colder Arctic circumpolar vortex (Orsolini and Limpasuvan, 2001;Schnadt and Dameris, 2003). A cold polar vortex allows the development of polar stratospheric clouds, which leads to greater ozone depletion over the Northern Hemisphere (Harris et al, 2010). Moreover, during the positive NAO phase, a ridge of high air pressure develops over central Europe (Hurrell, 1995), which usually leads to little cloudiness, enabling a more frequent occurrence of days with EUV 90+ .…”

Section: Very High Erythemal Uv Radiation Daily Dosesmentioning

confidence: 99%

Reconstruction and analysis of erythemal UV radiation time series from Hradec Králové (Czech Republic) over the past 50 years

et al. 2018

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Abstract. This paper evaluates the variability of erythemal ultraviolet (EUV) radiation from Hradec Králové (Czech Republic) in the period 1964-2013. The EUV radiation time series was reconstructed using a radiative transfer model and additional empirical relationships, with the final root mean square error of 9.9 %. The reconstructed time series documented the increase in EUV radiation doses in the 1980s and the 1990s (up to 15 % per decade), which was linked to the steep decline in total ozone (10 % per decade). The changes in cloud cover were the major factor affecting the EUV radiation doses especially in the 1960s, 1970s, and at the beginning of the new millennium. The mean annual EUV radiation doses in the decade 2004-2013 declined by 5 %. The factors affecting the EUV radiation doses differed also according to the chosen integration period (daily, monthly, and annually): solar zenith angle was the most important for daily doses, cloud cover, and surface UV albedo for their monthly means, and the annual means of EUV radiation doses were most influenced by total ozone column. The number of days with very high EUV radiation doses increased by 22 % per decade, the increase was statistically significant in all seasons except autumn. The occurrence of the days with very high EUV doses was influenced mostly by low total ozone column (82 % of days), clear-sky or partly cloudy conditions (74 % of days) and by increased surface albedo (19 % of days). The principal component analysis documented that the occurrence of days with very high EUV radiation doses was much affected by the positive phase of North Atlantic Oscillation with an Azores High promontory reaching over central Europe. In the stratosphere, a strong Arctic circumpolar vortex and the meridional inflow of ozone-poor air from the southwest were favorable for the occurrence of days with very high EUV radiation doses. This is the first analysis of the relationship between the high EUV radiation doses and macroscale circulation patterns, and therefore more attention should be given also to other dynamical variables that may affect the solar UV radiation on the Earth surface.

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A closer look at Arctic ozone loss and polar stratospheric clouds

Cited by 53 publications

References 46 publications

Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses

Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses

Ground-based stratospheric O<sub>3</sub> and HNO<sub>3</sub> measurements at Thule, Greenland: an intercomparison with Aura MLS observations

Reconstruction and analysis of erythemal UV radiation time series from Hradec Králové (Czech Republic) over the past 50 years

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A closer look at Arctic ozone loss and polar stratospheric clouds

Cited by 53 publications

References 46 publications

Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses

Comparisons of polar processing diagnostics from 34 years of the ERA-Interim and MERRA reanalyses

Ground-based stratospheric O&lt;sub&gt;3&lt;/sub&gt; and HNO&lt;sub&gt;3&lt;/sub&gt; measurements at Thule, Greenland: an intercomparison with Aura MLS observations

Reconstruction and analysis of erythemal UV radiation time series from Hradec Králové (Czech Republic) over the past 50 years

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Ground-based stratospheric O<sub>3</sub> and HNO<sub>3</sub> measurements at Thule, Greenland: an intercomparison with Aura MLS observations